EPA: DIOXIN DOES CAUSE CANCER IN HUMANS

An explosion at a Hoffman-LaRoche chemical plant in Seveso,
Italy, in 1976 sent a cloud of the herbicide 2,4,5-T over the
surrounding countryside, contaminating several thousand people.
Dioxin is created as an unwanted by-product during the
manufacture of 2,4,5-T, so the Seveso population was exposed to
dioxin. For years, optimists have been pointing to Seveso
saying, "Dioxin doesn't cause cancer in humans--look at Seveso."
Now a new study in the journal EPIDEMIOLOGY reveals that people
exposed to dioxin during the Seveso explosion have begun to
exhibit excessive numbers of cancers.[1]

Dr. Linda Birnbaum, director of environmental toxicology for U.S.
EPA [Environmental Protection Agency], told the Associated Press
that the new study "is one more nail in the coffin" for
dioxin.[2] Birnbaum, who is coordinating EPA's multi-year
"scientific reassessment" of dioxin said, "This, together with
other studies, clearly supports that dioxin has the potential to
cause cancer in people, just as it does in every animal it's been
tested in. The weight of the evidence is becoming overwhelming,"
she told AP reporter Paul Raeburn.

The area around Seveso has been divided into three zones, called
A, B and R. The small A zone was most heavily contaminated, but
its 724 residents were evacuated. ("Heavy" contamination means
that each square yard of land contained 13 to 494 micrograms of
dioxin; a microgram is a millionth of a gram and there are 28
grams in an ounce.) The B zone was less heavily contaminated but
its 4824 residents were not evacuated; zone B contained 43
micrograms of dioxin per square yard of soil, or less. The R
zone was even less contaminated (average contamination being 4.3
micrograms per square yard), so its 31,647 residents were
probably exposed to low levels. Another 181,579 people living
beyond zone R serve as a control group living in
"noncontaminated" areas.

The greatest cancer increase has occurred in zone B. In zone A
the numbers are small and no significant cancer increases have
occurred. In zone R one kind of cancer has increased: soft tissue
sarcoma. Previous studies have linked dioxin exposure to soft
tissue sarcoma in humans.

In zone B, among women there has been an observable increase in
cancers of the gall bladder and biliary tract (the system that
delivers bile from the liver to the small intestine), and in
cancers related to the blood-forming system (multiple myeloma and
myeloid leukemia).

Among men in zone B, there were observable increases in cancers
of the blood-forming system, and in one kind of non-Hodgkin's
lymphoma (a cancer of the lymph system called
lymphoreticulosarcoma).

This new study only covers the period 1976 through 1986--10 years
after the Seveso accident. Since most cancers take longer than
10 years to develop, the cancers reported in this study may
represent only the earliest signs of more trouble to come.

This Seveso study is not the first to indicate that dioxin causes
cancer in humans. [3-10,14,15] Swedish researchers in the late
1970s began reporting that exposure to phenoxy herbicides (2,4-D
and 2,4,5-T) caused a 3-fold to 6-fold increase in the risk of
soft tissue sarcomas and lymphomas. Phenoxy herbicides are
contaminated with dioxin during manufacture.

Monsanto Corporation, a major manufacturer of phenoxy herbicides,
in the late 1970s and early 1980s sponsored studies of workers
that the company had exposed to dioxin, and these studies showed
no increased cancer deaths among exposed workers. However, the
Monsanto studies have been criticized by a report from the
National Research Council, [11] which says Monsanto's studies were
"plagued with errors in classification of exposed and unexposed
groups, according to some reports, and hence have been biased
toward a finding of no effect." A 1990 analysis of Monsanto
workers, conducted by the National Institute for Occupational
Safety and Health, reported a statistically-significant increase
in soft tissue sarcomas. [12]

As part of its multi-year scientific reassessment of dioxin, EPA
recently published a draft review of all scientific data linking
dioxin to cancer and other health effects in humans. [13] The
EPA's draft document concludes that four separate
studies[8,9,14,15] of workers exposed to dioxin have revealed an
"overall increased mortality from all malignancies combined."
EPA speculates that dioxin's ability to mimic hormones gives
dioxin the capacity to cause cancer in many different organs and
bodily systems in humans. [13, pg. 7-7]

There seems to be little room left for doubt: As the EPA's
"scientific reassessment team" told then-chief of EPA, William
Reilly, January 27, 1992: "Dioxin does cause cancer in humans."
(See RHWN #283.)

It therefore seems that EPA now has little choice but to declare
dioxin a class A carcinogen, i.e., one known to cause cancer in
humans. This would have far-reaching implications for public
health policy. (A public hearing to discuss the new EPA
document, and its implications, is scheduled for 9-to-5 September
7 and 8, 1993, at the Ritz-Carlton Hotel in Pentagon City,
Arlington, Va. If you want to reserve time to speak, contact
Helen Murray of Eastern Research Group: (617) 674-7374. The
meeting will be full and space is limited, so we suggest you
arrive by 8 a.m. if you want a seat.)

An editorial in the September issue of EPIDEMIOLOGY points out
some of the public policy implications of the conclusion that
dioxin causes cancer in humans. [16] The author of the editorial,
Swedish dioxin researcher Olav Axelson, says that the "biological
effects of TCDD [dioxin]" are "a first order public health
concern." Axelson says "there seems to be an urgent and costly
need to change or improve industrial and other processes so as
not to produce dioxins (and the toxicologically similar
chlorinated dibenzo-furans). For example, there is a need to
restrict the use of chlorine in paper bleaching. Incineration of
waste material at too low temperature should be avoided as well
as the 'combustion' of organochlorine compounds in general,"
Axelson says.

Dioxin is produced by every municipal solid waste incinerator
ever tested; it is produced by all hazardous waste incinerators,
cement kilns and BIFs [boilers and industrial furnaces] that burn
chlorinated wastes. It is produced by the manufacture of many
pesticides (85% of which involve chlorine). It is produced by
metal smelters, and paper mills, and probably by other common
industrial processes. Although there is now little doubt that
dioxin causes cancer in humans, translating that into public
policies that genuinely protect public health will create a
political firestorm. Once again, EPA chief Carol Browner faces a
series of decisions that will define clearly and unmistakably
which side she and Bill Clinton are on.
--Peter Montague, Ph.D.